1. Answer the following questions, (i) Why do the plates move? (ii) What are exogenic and endogenic forces? (iii) What is erosion? (iv) How are flood plains formed? (v) What are sand dunes? (vi) How are beaches formed? (vii) What are ox bow lakes?
Answers
i) The heat from radioactive processes within the planet's interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
ii) The forces working over the earth's surface are known as exogenic forces, while those working within the earth's surface are called endogenic forces. They act tangentially to the earth's surface, as in plate tectonics.
iii) Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.Most erosion is performed by liquid water, wind, or ice (usually in the form of a glacier). If the wind is dusty, or water or glacial ice is muddy, erosion is taking place.
iv) At the time when the river overflows its banks, this leads to flooding of nearby areas. As it floods it does deposit layer of fine soil and other materials called sediments along its bank. This leads to the formation of the flat fertile floodplain.
v) A dune is a mound of sand formed by the wind, usually along the beach or in a desert. Dunes form when wind blows sand into a sheltered area behind an obstacle. Dunes grow as grains of sand accumulate. Every dune has a windward side and a slipface.
vi) A beach forms when waves deposit sand and gravel along the shoreline. and pebbles. Over time they are worn smooth from being rolled around by waves. The rocks usually reflect the local geology.
vii) An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river. Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water.